Expansible abrasive wheel



Feb. 24, 11959 J. R. MaClNTOSH ET AL EXPANSIBLE4 ABRASIVE WHEEL Filed Aug. 6, 1957 4.. www

9000000 O O eoOOOOO O O o o o o o o o o gazier-E Mo. o'd-cysk ,50x72 @MQ/@afm Jabra United States Patent() M This invention is concerned with an expansible abrasive wheel, and more especially to a wheel of such 0character Y having a relatively rigid hub and a resilient, expansible rim mounted thereon. A

An expansiblel wheel of the type herein considered,` is disclosed in ourcopending patent application, Serial No. 560,981, .filed January 24, 2,801,504, of which this is ac ontinllation-in-part.v In that application, the rim was noted as formed of rubber or similar resilient material having the characteristic of expanding under the `influence of centrifugal force thereon when the wheel was rotated in excess of a predetermined velocity. Such expansion of thewheel to an enlarged diameter enabled an endless' abrasive belt to be quickly and easily mounted upon the rim or to be removed therefrom; yet when the wheel was rotated, the abrasiveband 1956, now Patent No.

2,874,519 Patented Feb. V24,'1'959 -Z axis ofthe hub-the passages having irregular or roughened surfaces, or having thin diaphragms or membranes therein to prevent a smooth iiow of air through the passages when the wheel is rotated.

In use of an expansible abrasive wheel of the type described, it is found that there is a slight tendency for the endless abrasive belt to shift laterally at the time the wheel is gaining momentumand prior to the expansion to the full diameter thereof Vpermitted by the band; and similarly, the same tendency toward lateral shifting is experienced when'the velocity of the wheel is decreasing to 1ero. In certain instances during anactual abrading operation, the belt may tend to shift laterallyto s ome degree if the belt'and workpiece abradedv thereby are engaged at an irregular angle-that is to say, at an angle such that a force component inthe lateral or transverse direction is applied thereagainst as well as the usual force component normal thereto. l O V It has been discovered that this tendency of thebelt to shift with respect to the expansiblerirn can be substantially negated by embossing the circumferential surface of the rim in a manner such that the belt has a greater ten-A dency to cling thereto, and the provision of a wheel having this advantage is a further object of this invention. Yet another object is to equip the circumferential surface of t an expansibleabrasive wheel adapted to have an endless` was frictionally grippedby the rim and held in placeV at continuous flexing ofthe belt kicked or propelled abraded particles: therefrom and thus prevented glazing, and it l permitted the grit or abrasive material of the belt to more effectively cutinto a work material in contrast to impacting the same (which, if continuously repeated, caused the grit to, chip oft). e

Z'Ihe passages, however, did not extend continuously across the rim, but instead terminatedinteriorly and alterntely on opposite sides so as to give the wheel balance. It has now been found that the passages can be extended completely through the rim` from side to side thereof, in contrast to the passages which terminated midway of the rim, edges-provided thatV the passages are interrupted or otherwise constructed so as to prevent thelunrestricted flow of air therethrough which causes a piercing whistle r noise when the wheel is rotated at its operational velocity. `In accordance withthis discovery, an object of the invention is to provide a rotatable wheel havingpas-I sageseextending transversely therethroughwhich do not create undesirable noise because of airY flow in the passages.

Another objectV of the invention is to provide an expansible wheel :structure having transversely extending passages therein' that are designed so as to preventv or to so interfere vwith the air flow therein, that turbulence is abrasive belt mounted thereon, with a design configuration comprising a plurality'of recesses which cooperate with and are implemented by the exing or yielding of the ex- .pansible wheel as described hereinbe'fore, `to draw the belt tightly against the surface of the Wheel'and thus rninimize its tendency for lateral shifting. ,l Still a further object is to Vequip the `expansible rim of an abrasive wheel with a plurality of-Ydepressions or recesses, that may be a'plurality of seprated'recesses rof minute diameter or serpentine grooves of minute width, which suck the belt toward the surface of the rim because of a slight vacuum that develops as the normal'air within such; recesses is expelled during liexing of the beltand underlyingrim." Additional objects'and advantages of the invention will become apparent as the specificationfdelvelops. Y i

Embodiments of the invention-are illustrated in the aecompanying drawing, in which y Figure l is an end View iu Velevation of'an expansible abrasive wheel embodying the invention, and in which an endless abrasive belt mounted upon the wheel is broken away to show the wheel surface; Figure 2 is` a side View in elevation of the wheel illustrated in Figure l, butwith the endless abrasive beltiremoved; Figure 3 is a broken vertical sectional viewrtaken along the line 3 3 of Figure 2; Figure 4 is an endview in elevation of a modified abrasive wheelstructure; and Figure 5` is a broken vertical sectional view similar to that of Figure 3, but being taken through the modified wheel structure of Figure 4.

createdwhereby undesirable noise developed by a` c onf tinuous or uninterrupted air flow is substantially mini-V mized. Still another object is that of providing an abrasive`wheel having an expansible, resilient rim adapted to carry anabrasive belt circumjacent thereon, and which is provided with plurality `of passages oriented in ,arcuadapted to have` an endless abrasive belt or band 14 mounted in circumjacent relation thereon.

The band 14 has substantially the same Width as that o f the rim 13, and the inner diameter thereof is slightp v Y i l n t lyfgreater than the outerdiameter of `vthe rim whenlthe ately spaced relation defining a circle about the rotational wheel is at rest; but Vwhen the wheel is rotated, centrifugal force causes the Vrim -to expand into tight frictional engagement with the Abelt 14 so as to firmly anchor the belt thereon. As hasbeen brought out hereinbefore, there are in certain `instances a tendency for the belt 14 to shift laterally with respect to the `rim 13, and we have found-that this tendency can .be .substantially obviated by equipping the circumferential surface ofthe rim with a plurality of recesses or depressions therein which, as shown .in Figure l, are in the form of substantially .identical grooves or channels 15 rarranged. in spaced, side-by-side relation.

The precise number of grooves 15 will depend upon the width of the rim 13 and, for example, with a wheel having a rim width of aboutone inch, there .may be 20 such grooves. Preferably, the grooves Lextend completely -about the circumference of therim, although interruptions therein are permissible. The grooves. Yare quite shallow, and in the example set forth may have. a depth of about 1,62 of aninch. It is most desirable that the grooves have an irregular or serpentine configuration, as lshown in Figure 1, for this will prevent scouring or marring of the work material abraded by the wheel as could be experienced if the grooves were straight.

In further accordance with the example, the maximum total amplitude of the generally sinusoidal wave pattern (a complete cycle) illustrated in the specific embodiment of Figure 1, and which is designated as the dimension A in that figure, may be about oneexght of an inch. The .dimension B represents the entire curve length (that is, a complete sinusoidal cycle),` and should have a length of about 'one and one-half inches. It should be understood that the specic `figures are set forth solely as examples, and the `dimensions represented thereby could .be varied sharply.

The modified wheel structure illustrated in Figures 4 and 5 is denoted with the numeral 16, and may be structurally similar to the wheel heretofore described. It will be noted in Figure 4 that the depressions or recesses take the lform of small individual pocks or dents 17 oriented into transversely lextending rows 18 and circumferentially.extending rows r19. In the specific illustration, there are three such circumfer ential rows 19, and the vtransverse vrows .18 may vbe spaced apart about one-eighth of an inch. Each of the recesses 17 may have a diameter oftabout 3A@ of an inch, and a depth of about 0.()20 inch. It will be Vunderstoodthat considerable dimensional variation may be incorporated in the design shown in Figure .4, `and the number of rows 19 is in no sense fixed. Also, while the rows 19 are straight, they could be arranged in other configurations such as the serpentine configurattion shown in Figure 1.

Returning to the wheel structure 10 shown in Figures 1 through 3, it will be noted that the rim 13 thereof is provided with a plurality of passages 20 and 21 extending transversely thereof. The passages 20 are oriented in spaced apart relation, and define an inner circular row designated generally with thenumeral 22 having its center at the center or rotational axis of the hub. The outer passages 21 are also positioned in spaced apart relation, and define an outer row denoted generally with 23 which is concentric with the row 22. The passages 20 of the inner row and 21 of the outer row are offset angularly with respect to each other, and define an alternate or staggered interrelation.

Referring to Figure 3, it will be seen that each of the passages 20 and l21 is interrupted intermediate the ends thereof with athin .membrane 2.4 and 25 respectively, whichmay or may not be imperforate. branes may b e located at any convenient position intermediate the ends of the passages, and in the vspecific illustration are adjacent an end portion thereof. 'The structure shown has the membranes 25 of thepassages 21 .located adjacent one side of the rim I3, while the membranes' 24 are fadjacent'the opposite side'of the-rim.`

These mem- In the modified wheel structure of Figure 5, inner and outer transverse passages are also incorporated in the rim 26 thereof, and aredesignated with the numerals 27 and 28. Such passages'y may be identical to the passages Zfi and 21 with respect to the locations and arrangement thereof, but it will be noted, do not have a membrane interrupting the continuity thereof. Rather, the surfaces defining the interior of the passages are irregular, and such irregularity may be provided in any suitable manner as, for example, by piercing the rim to form the passages therein.

The passages through the rims of the respective wheels 10 and 16 are shown in generally rectangular` form, and each has 4a slight curvature corresponding yto the circular arc on which they lie. However, the passages may have other configurations, and may be round, or teardrop configuration, etc.

In use of the structures described, the respective abrasive wheels are mounted upon a ,shaft andare rotatably driven thereby. The endless. abrasive .belt 1.4 which is initially loose on the wheel, is tightly .gripped as the rim expands and the assembly is then in readiness for an abrading operation. The transversely extending passages serve the function of softening the expansible rim in its entirety without decreasing theunit firmness thereof, and .together with the natural resilience of the rims serve as a cushion whereby the .rim is-depressed at the point of engagement thereof .with a workpiece. As ysoon as any such depressed point is .rotated beyond the workpiece, it springs outwardly and toits normal position. Thus, a constant .or repetitive flexing occurs at each point along the rim .as the wheel is rotated in ,an abrading operation.

This fiexing has the advantage of expelling abraded particles from the belt 14, thereby keeping it clean with the result that it does not glaze, and with the further result that the abrasive grit does not chip whereupon the belt has relatively long life and cuts` more effectively and rapidly. The flexing of the wheel also serves to move air through the transverse passages, .and `the vfiow. of air therethrough carries away heat and tends to keep the rim relatively cool. It has been .found that when the passages have a configuration that interrupts or .disturbs the fiow of air therethrough, the wheel does not whistle or otherwise develop objectionable ynoises during use. .The membranes 24 and 25 serve to so interrupt the ow of air through the passages, and the irregular configuration of the surfaces .of the passages 27 vand 28 also achieves a sound eliminating result by disturbing the air fiow through the passages. Apparently, the roughened or irregular surfaces are sufficient to create turbulence of the air and thereby prevent a smooth ow which, it is believed, is the cause of the objectionable noise.

The recesses in the circumferential surface of the Iexpansible rims, which are in the form of shallow .grooves 15 in Figure 1 and4 individual recesses of vdiminutive size in `Figure 4, vtend to more firmly aflix the `belt '14"in its circumjacent relation upon the rims and thereby minimize the tendency for lateral displacement thereof during starting and stopping ofthe wheel, and during abrading operations wherein laterally oriented forces are applied against the belt. It appears that thisholdingaction is provided because of thefiexing of the rim, and consequently a result of the inclusion of the transversely vex` tending passages. It is believed that the fiexing of the rim expels air from the grooves 15 and recesses 417so that aslight vacuum developsv therein. Thisyvacuuntlfor negative force in bein-g vapplied tothe-belt 14, causes it to adhere even more tightly to the trim. ;Moreover,the edgesof the recesses as a result of such suction, tend to bite into the belt and Ythereby increase the frictional re sistance to movement thereof.

While in the lforegoing specification embodiments of the 'invention have been set forth "in considerable length pansible, resilient rim adapted to be rotatably driven,

said rim being diametrically dimensioned so as to receive an endless abrasive belt thereon when the rim is at rest but to expand into gripping engagement with such belt vwhen the rim is rotated at a predetermined Velocity,

said rim being provided with a plurality of shallow recesses about the circumferential surface thereof to resist lateral shifting of such belt thereon, said rim having a plurality of passages extending transversely thereof provided with means for disturbing the movement of air therein to minimize sound which would otherwise be created by the movement of air therein.

2. The wheel structure of claim 1 in which said recesses comprise a plurality of circumferentially extending grooves.

3. The wheel structure of claim 2 in which said grooves have an elongated curvature along the length thereof to define a departure from a straight circumferential line.

4. The wheel structure of claim 1 in which said recesses comprise minute depressions located throughout the circumferential surface of said rim.

5. The Wheel structure of claim 4 in which said depressions are oriented in a plurality of circumferentially and transversely extending rows.

6. In a wheel structure of the character described, a wheel adapted to be rotatably driven, said wheel being provided with a plurality of passages extending transversely therethrough, and means for disturbing the ow of air through said passages when said Wheel is rotated to substantially minimize sound which would otherwise be created by the ow of air therethrough.

7. The wheel structure of claim 6 in which each of said passages is provided with a membrane intermediate the ends thereof to effectuate such disturbance of the air flow therethrough.

8. The wheel structure of claim 6 in which said passages have irregular walls defining the same to provide such disturbance of the air ow therethrough.

9. In an abrasive wheel structure of the character described, a resilient, expansible rim adapted to be rotatably driven, said rim being dimensioned to slidably receive an endless abrasive belt thereover when the rim is at rest and to expand into tight resilient engagement with such belt when the rim is rotated, said rim being provided with a plurlity of passages extending transversely therethrough, and air flow disruption means within said passages for interfering with the ow of air therethrough.

10. In an abrasive Wheel structure of the character described, a resilient, expansible rim adapted to be rotatably driven, said rim being dimensioned to slidably receive an endless abrasive belt thereover when the rim is at rest and to expand into tight resilient engagement with such belt when the rim is rotated, said rim being provided with a plurality of passages extending transversely therethrough, and air flowdisruption means within said passages for interfering with the ow of air therethrough, said rim being provided with a plurality of recesses along the circumferential surface thereof operative to resist lateral movement of such a belt positioned thereon.

11. The wheel structure of claim 10 in which said passages are oriented in spaced apart relation adjacent the circumferential surface of said rim and aligned in a row defining a circle concentric therewith, and in which said recesses are relatively shallow.

12. The wheel structure of claim 1l in which said disruption means comprise projections extending interiorly into said passages, and in which said recesses are aligned in circumferentially extending orientation.

13. In a structure of the character described, a Wheel adapted to be rotatably driven and comprising a relatively rigid hub having a centrifugally expansible rim anchored thereon diametrically dimensioned so as to slidably receive an endless abrasive belt when the rim is at rest but to expand into gripping engagement with such belt when the rim is rotated at a rate in excess of a predetermined velocity, said rim being provided with a plurality of passages extending transversely thereof equipped with means for disturbing the ow of air therein when said Wheel is rotated to substantially minimize the sound which would otherwise be created by the movement of air therein.

14. The structure of claim 13 in which said rim is provided along the circumferential surface thereof with a plurality of relatively shallow recesses effective to resist lateral shifting of such a belt positioned thereon.

15. The structure of claim 14 in which said recesses extend along the circumferential surface of said rim.

16. The structure of claim 14 in which said recesses comprise a plurality of relatively small depressions oriented in spaced relation along the circumferential surface of said rim.

References Cited in the tile of this patent UNITED STATES PATENTS 257,308 Flagg May 2, 1882 277,097 Abbe May 8, 1883 2,687,600 Larson Aug. 31, 1954 2,687,601 Larson v Aug. 31, 1954 

